Monster House
Full health
While playing the game, hold L1 + R1 and quickly press X(3), Triangle.
Full secondary ammunition
While playing the game, hold L1 + R1 and quickly press Triangle(2), X(2).
All gun upgrades for all characters
While playing the game, hold L1 + R1 and quickly press Square, Triangle, Square, X, Square, Circle, Square(2).
All toy monkeys and art gallery images
While playing the game, hold L1 + R1 and quickly press Triangle, Circle, Triangle, Circle, Square(3), X.
Completion bonuses
Successfully complete the game to unlock the Hard difficulty setting and the Ruby Key.
Overflowing toilet
When you get to the bathroom in Chapter 1, start flushing the toilet until it overflows. Stay in the bathroom and eventually you will go to heaven.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art / Original